1. Field of the Invention
The present invention relates to leavening acid compositions for baked goods and more particularly monocalcium phosphate leavening acids which have excellent control release properties.
2. Technology Description
Chemical leavening systems have been known for over 100 years. The replacement of yeast to induce the process of fermentation by a carbonate alkali which is subjected to the neutralizing action of an acid has reduced the amount of time and materials required for the preparation of baked goods. From this early beginning various leavening systems have been invented and sold as baking powders which contain not only the leavening alkali and the acid employed to neutralize the acid, but also fillers which enabled convenient measurement, handling and storage of such baking powders.
Leavening systems have long been known to comprise two basic ingredients. The first, of course, is the leavening acid such as cream-of-tartar, various phosphoric acids such as orthophosphoric acid, pyrophosphoric acid and the partial salts thereof such as monocalcium phosphate, sodium acid pyrophosphate, and any other suitable, edible, non-toxic acid which would not impart an undesirable taste to the resultant baked goods. Such acids have been known as "acidulants", or "baking acids" but more commonly as "leavening acids".
When added to a moist batter or dough, the acid reacts with a carbon dioxide liberating compound included in the batter or dough to yield the gas necessary for leavening. The rate of gas evolution is an important consideration determining largely the volume, density and texture qualities which will be imparted to the final baked product. This rate must occur within rather narrow limits for some applications such as in the preparation of prepared, canned dough for biscuits. Also, leavening requirements differ widely among the various baked goods for each of these demands a particular speed of evolution to ensure highest quality products. One of the principal factors with respect to the speed of evolution of carbon dioxide is the reactivity of the carbon dioxide producing material.
It is a primary objective when using leavening acids to modulate and control the carbon dioxide liberation kinetics to yield a suitable final baked good product. More particularly, it is desirable to limit the reactive effect of water with the leavening acid. Ideally, the leavening acid would be designed so that it would not be reactive at the time of kneading or cold storing of the dough but would be reactive during heating, where the leavening of the final product takes place.
Particularly useful leavening acids are phosphate materials, and more specifically monocalcium phosphate. This acid is considered desirable as a commercial candidate as it does not possess sodium and has no aftertaste. While monocalcium phosphate does not possess sodium it has been difficult to adequately control its reaction rate which results in the release of carbon dioxide bases at various stages during the baking cycle. The fundamental problem with the use of monocalcium phosphate is that it liberates gas at too fast a desired rate. As a result, its commercial use has generally been limited to being a part of a leavening acid blend. Such blends can be less than optimal because they either may contain sodium, for example blends of monocalcium phosphate with sodium aluminum phosphate or sodium pyrophosphate, or may not have a completely bland taste.
It has been known to regulate the speed of carbon dioxide evolution by control of the reactivity of the leavening acid. Numerous attempts to control the speed of reaction of the leavening acid are known in the art. Typical examples include U.S. Pat. No. 3,034,899 to Tucker wherein a finely divided calcium salt is combined with the acid to control the speed of reaction.
Calcium salts have been employed in chemical leavening systems from its earliest days. A typical example of such use is found in U.S. Pat. No. 315,831 to Peters. However, such calcium salts as taught in Peters are relatively slow acting and have not provided satisfactory performance as the carbonate factor particularly in comparison with the alkali metal salts. Although calcium salts such as calcium carbonate have been employed for various purposes such as preservatives for the leavening acid, etc. as noted in U.S. Pat. Nos. 4,388,336 and 4,526,801, such carbonates do not provide the reactivity desired for a carbonate factor in baked goods.
The use of so-called "coated" monocalcium phosphate where the monocalcium phosphate has a thin coating of phosphate surrounding its acid core is known in the art. However, the "coating" does not provide the reaction kinetics that is ideally preferred and typically can only be used as part of a blend composition. Such materials are disclosed in U.S. Pat. No. 2,160,232. To produce the coated materials, the starting monocalcium phosphate material is subjected to heat treatment at a temperature above about 140.degree. C. The reference further states that the materials should not be heated to above 230.degree. C. as it is alleged that this can cause rapid conversion of leavening acid to a pyrophosphate form. The reference further suggests that the neutralizing value, i.e., the amount of sodium bicarbonate which is completely neutralized by 100 parts by weight of the acid phosphate, of the acids so produced is between about 83 and 88. While this technology has improved the controlled reactivity of the monocalcium phosphate its performance is inferior as compared to sodium containing leavening acids such as sodium acid pyrophosphate and sodium aluminum phosphate.
U.S. Pat. No. 2,160,700 discloses that anhydrous monocalcium phosphate can be prepared by crystallization from an acid solution. A preferred method of preparing crystalline anhydrous monocalcium phosphate is also disclosed in this patent. In the method, a slight excess of lime is added to a relatively concentrated phosphoric acid solution to spontaneously produce a reaction temperature in excess of 140.degree. C. The temperature is controlled in a range above 140.degree. C. but below a temperature at which substantial amounts of pyrophosphate form. The temperature is usually controlled by the rate of lime addition. The reaction is continued until a substantially dry mass of solid anhydrous monocalcium phosphate is produced.
U.S. Pat. No. 3,109,738 is directed to a leavening acid composition which is a mixture of sodium aluminum phosphate and anhydrous monocalcium phosphate. This composition demonstrates excellent release properties but requires the use of a sodium containing acid.
U.S. Pat. No. 3,954,939 is directed to a monocalcium phosphate having reduced caking tendencies by admixing water with a monocalcium phosphate composition having a loss on ignition between about 14 and about 17%, permitting the water and monocalcium phosphate to remain in contact for a sufficient length of time to form a hydrated monocalcium phosphate composition with a loss on ignition between 17 and 21.5%, and drying the monocalcium phosphate composition to a free moisture content below 1% and preferably below about 0.5% if the admixture has a free moisture content above this level.
Accordingly, it would be desirable to produce a monocalcium phosphate leavening acid whose release rate properties can be tightly controlled for optimal use for a multiple of baking applications.